。
She loves him very much.
Literal
She [topic-は] him [object-を] very is-loving.
愛する ('to love') is a する-verb (a Sino-Japanese 漢語 noun + する), and like other する-verbs marks its object with を. The ~ています form puts the love into the ongoing-state reading — 'is in a state of loving' — which is how Japanese typically expresses 'loves' as a present condition. 愛する is a comparatively heavier word than 好き ('like, fond of'); reserved for romantic, deep, or family love.